The present invention relates to a structured semiconductor body of the type comprising at least a plurality of differently doped monocrystalline silicon semiconductor regions delimited by at least one barrier region which prevents undesirable electrical current flow, as well as to a method of forming the structured semiconductor body.
The invention can be used, in particular, for the manufacture of transistors and/or integrated circuits (IC's) which are based on a silicon (Si) substrate.
A known exemplarily selected bipolar semiconductor structure of the above type which can be produced with the aid of presently customary processes, e.g. masking by means of lithography, oxidation, diffusion, implantation, epitaxy and metallization processes, is shown in FIG. 1.
According to FIG. 1, an n+doped so-called buried semiconductor zone (buried layer) 2 is initially produced by the known methods on an exemplary p- doped Si substrate 1, e.g. a monocrystalline Si wafer having a diameter of about 75 mm, a thickness of about 0.5 mm and a (100) crystal orientation. This is followed by the production of the semiconductor regions required for a bipolar transistor, i.e. an n-doped region 3, an n+ doped collector contact region 4, a p doped base region 5 as well as an n+doped emitter region 6 disposed within the base region 5. To avoid undesirable electrical current flow, this semiconductor structure is delimited by at least one barrier region 7, which in this example is configured as a p+doped semiconductor region extending from the outer surface of the semiconductor body into the p- doped substrate 1. Electrical short circuits are avoided in that this semiconductor structure is covered by an oxide layer 8, e.g. of silicon dioxide, into which contacting windows have been etched. The base terminal B, the emitter terminal E and the collector terminal C for the bipolar transistor are produced by applying a structured metal layer 9 to the outer surface of the oxide layer 8 so as to contact the regions 5, 6 and 4 respectively via the contacting windows.
In such a structured semiconductor body, the barrier region 7, which is shown, for example, as a semiconductor region doped as a blocking pn-junction, can be produced only by uneconomical insulation diffusion and/or insulation oxidation processes. The barrier region 7 is here intended to avoid undesirable current flow, e.g. between adjacent transistors of an integrated circuit.